The present invention relates generally to the field of electronic and microelectronic devices, and more particularly relates to polymeric films for use in electronic and microelectronic devices, and to methods for their production.
Many varieties of polymeric films have been employed in the electronics and microelectronics industries. As industry-wide pressure increases to produce smaller and smaller electronics components, the fabrication of ultra-thin films for electronics applications becomes increasingly important. In the past, polymeric films have been employed in microelectronics applications as insulating materials, resist films, gas separation membranes, diffusion barriers, corrosion barriers, surface modification or surface sealing of porous substrates, lubricating layers for small scale machining operations (e.g., nanomachining applications) and others. Metal and metal alloy films have also been employed for these applications.
As demand increases for new wiring and electronic component materials, and as a result of the attractive qualities of copper for wiring and electronic components, the need for efficient diffusion barriers to copper rises. Copper's low electrical resistivity and high resistance to electron migration yield improved device reliability in devices which employ copper. However, copper diffusion into silicon and silica substrates at elevated temperatures can lead to device degradation. Attempts to develop efficient copper diffusion barriers for these applications have led to a number of metal film materials. J. Imahori, et al., Thin Solid Films 301:142 (1997) lists several metal and metal alloy films including TaC, W, Ta, Ta--Si, W--N, Ta--N, Ti--N, Ti--Si--N, and Ta--Si--N films which have been investigated for use as copper diffusion barriers. In addition, U.S. Pat. No. 5,164,332 to Kumar proposes a copper metal alloy as a copper diffusion barrier between a copper feature and an oxygen-containing polymer. The diffusion barrier is formed by coating a metal (e.g., Al) on the copper feature and heating the metal and copper to form an alloy. To be effective, materials employed as copper diffusion barriers should exhibit low thermal coefficient of expansion, ease of processing, good adhesion to copper, and minimal reactivity with copper and other microelectronics materials. Often, particularly preferred copper diffusion barriers also exhibit a low dielectric constant as well.
In addition to the need for copper diffusion barriers, there also remains a need in the art for thin films which can be useful as insulating materials, resist films, lubricating layer materials, and surface modification and sealing materials. Many varieties of dielectric or insulating materials have been employed in microelectronics devices. Silicon dioxide, silicon nitride, polyimides, and polyphenylene polymers are examples of materials which have been proposed for these applications. For example, U.S. Pat. No. 4,588,609 proposes one method of preparing polyparaphenylene polymer films by photochemical vapor deposition. These materials can be difficult to fabricate and process, and producing the necessary thin layers of these materials for use in microelectronics has been challenging.
There remains a need in the art for effective copper diffusion barriers and insulating materials. There further remains a need in the art for copper diffusion barriers which prevent the diffusion of copper atoms or ions at elevated temperatures. In addition, there remains a need in the art for copper diffusion barriers which can be fabricated as ultrathin films. There also remains a need in the art for methods of producing polymer films for use in microelectronics applications. In one aspect, the present invention provides a copper diffusion barrier for use in electronics and microelectronics applications. The present invention also provides a method for producing thin polymer films on substrates for use in electronic, particularly microelectronic, devices.